Funding:This work was supported by the STFC UK (grant ST/M003590/1) and the Leverhulme Trust (International Network Grant IN-2015-012). H. Harrison is supported by STFC UK and the JAI for her DPhil.Smith-Purcell radiation has been successfully used to perform longitudinal profile measurements of electron bunches with sub-ps lengths. These measurements require radiation to be generated from a series of gratings to cover a sufficient frequency range for accurate profile reconstruction. In past systems the gratings were used sequentially and so several bunches were required to generate a single profile, but modern accelerators would benefit from such measurements being performed on a bunch by bunch basis. To do this the radiation from all three gratings would need to be measured simultaneously, increasing the mechanical complexity of the device as each grating would need to be positioned individually and at a different azimuthal angle around the electron beam. Investigations into gratings designed to displace the radiation azimuthally will be presented. Such gratings could provide an alternative to the rotated-grating approach, and would simplify the design of the single-shot monitor by reducing the number of motors required as all of the gratings could be positioned using a single mount.

It is proposed to use the polarization of coherent Smith-Purcell radiation (cSPr) to distinguish between the cSPr signal and background radiation in a single-shot longitudinal bunch profile monitor. A preliminary measurement of the polarization has been carried out using a 1mm periodic metallic grating installed at the 8MeV electron accelerator LUCX, KEK (Japan). The measured degree of polarization at '=90° (300GHz) is 72.6 ±%. To make a thorough test of the theoretical model, measurements of the degree of polarization must be taken at more emission angles - equivalent to more frequencies.This work was supported (in parts) by the: STFC UK, the Leverhulme Trust, JAI University of Oxford and the Photon and Quantum Basic Research Coordinated Development (Japan).